PART I CHAZYAN AND RELATED BRACHIOPODS—COOPER 925 
Horizon and locality—Bromide formation (Pooleville member-zone 2) in 
Oklahoma: West of Nebo store, sec. 22, T. 2 S., R. 3 E., Murray County. 
6PIKINA sp. 3 
This is a species of medium size having fairly low convexity, prominent beak, 
and narrowly swollen umbo. The posterior half is characterized by costellae al- 
ternating in size, but at the anterior the costellae are nearly equal and number 4 
to the millimeter. The specimen is not like any other in the collection but is not 
complete enough for specific designation. 
Measurements in mm.—117851, length 18.0, midwidth 21.5, hinge width 
20.3?, height 4.5 ?. 
Described specimen.—117851. 
Horizon and locality—Edinburg formation (Cyrtonotella zone) in Virginia: 
In the railroad cut about $ mile east of Strasburg Junction, Strasburg (15’) 
Quadrangle. 
OPIKINA sp. 4 
A single specimen of fairly large size for the genus, having a somewhat nasute 
front and considerable height, is so poorly preserved that specific description is 
inadvisable. The specimen is significant, however, because of its occurrence in 
the Little Oak limestone. It is suggestive of some from the Ridley of West 
Tennessee. 
Measurements in mm.—123295, length 22.8, brachial length 19.7, midwidth 
23.0?, thickness 4.1, height 10.4. 
Described specimen.—123295. 
Horizon and locality—Little Oak formation in Alabama: At the junction of 
the Bailey Gap and Cahaba Valley roads, SWiSW3 sec. 13, T. 19 S., R. 2 W,, 
13 miles northeast of Newhope Church, Vandiver (15’) Quadrangle. 
OPIKINA sp. 5 
Plate 268, E, figures 16-24 
This is a variable or possibly a mixed species that occurs abundantly in the 
Whistle Creek formation of Catawba Valley. It is moderately large, fairly 
strongly convex, and with the convexity just anterior to the middle. The brachial 
valve is deeply concave. The muscle field of the pedicle valve is nearly circular 
and of moderate size. The species is quite unlike either of the Arline species 
and appears remarkably advanced for the earliest Opikina. 
Measurements in mm.—123292a, length 18.7, brachial length 17.1, midwidth 
22.5, hinge width ?, thickness 3.7. 
Figured specimens.—123292a-d. 
Horizon and locality.—Ellett formation (75 feet above the Knox dolomite) 
in Virginia: On Indian Run, # mile northwest of Lusters Gate, Blacksburg (15’) 
Quadrangle. 
Discussion—Unfortunately, the material collected is not good enough on 
